The present disclosure relates to an image reading apparatus that generates image data by reading a document.
The image reading apparatus reads a document with an image sensor and generates image data. The image reading apparatus is provided with a lamp irradiating a document with light. Based on the reflected light from the document, the image sensor reads the document. Some image reading apparatuses move a carriage including a lamp in the sub-scanning direction. As the carriage moves, the position irradiated with light moves in the sub-scanning direction, so that one sheet of the document is read. The carriage has a home position set for it. When a document is read, the carriage reciprocates with respect to the home position.
An image reading apparatus as described below is known. Specially, in a known image reading apparatus, an image reading portion is reciprocated in the sub-scanning direction by use of a driving source, and is arranged at the home position. When a fault occurs while the image reading portion is reading an image, the supply of power to the driving source is stopped. When a fault is resolved, the image reading portion is arranged at the home position. The image reading apparatus always tends to start image reading operation at the same position.
For example, consider a case where image data of a plurality of sheets of a document needs to be transmitted together. If a transmission job is started each time one sheet of the documents is read, setting of a transmission job needs to be repeated many times. To avoid that, an image reading apparatus may be provided with a continuous reading mode. The continuous reading mode is a mode in which a job is started after completion of reading of a plurality of sheets of a document.
As mentioned above, when the document placed on a document stage (platen) is read, the carriage may be moved in the sub-scanning direction. The movement of the carriage from the home position and the return of the carriage to the home position are repeated for each sheet of a document. In the continuous reading mode, each time a sheet of the document is read, the carriage reciprocates between the home position and an end part of the document. In this case, the movement distance of the carriage is large, and this may make it impossible to start reading of a next document immediately. A problem here is that it may take time to read a document because the movement distance of the carriage is large.
The known apparatuses mentioned above return the carriage (image reading unit) to the home position for each sheet of a document. The movement distance of the carriage can be large. Thus, they do not solve the problems mentioned above.